Knock-over blade structure for warp knitting machines



Oct. 15, 1968 w. DIEHL 3,405,543

KNOCK-OVER BLADE STRUCTURE FOR WARP KNITTING MACHINES Filed June 14, 1966 3 Sheets-Sheet l INVENTOR. WALTER L DIEHL pay/ m ATTORNEYS.

Oct. 15, 1968 Fig. 2

PRIOR ART WWLPW W. L. DIEHL Oct. 15, 1968 KNOCK-OVER BLADE STRUCTURE FOR WARP KNITTING MACHINES 3 Sheets-Sheet 5 Filed June 14, 1966 ATTORNEYS.

United States Patent 3,405,543 KNOCK-OVER BLADE STRUCTURE FOR WARP KNITTING MACHINES Walter L. Diehl, Gastonia, N.C., assignor to Cocker Machine & Foundry Company, a corporation of North Carolina Filed June 14, 1966, Ser. No. 557,550 1 Claim. (Cl. 66-86) ABSTRACT OF THE DISCLOSURE An immovable thin knock-over band suitable for the production of closely knit fabric made on high speed warp knitting machines.

This invention relates to an improved knock-over blade structure for Raschel and other types of warp knitting machines. I

More particularly, the improved structure of the present invention makes it possible to knit very fine or tight stitches closely adjacent each other in the warp chain at extremely high operating speeds.

In order to understand how the present apparatus attains these objectives, and the drawbacks of the prior art, reference will now be had to the drawings wherein:

FIG. 1 is a schematic view in side elevation showing the general features of a warp knitting machine, including needle bed, warp beam and take-up rolls that are utilized in connection with this invention;

FIG. 2 is a side elevation in partial section showing a knock-over band structure of the prior art;

FIG. 3 is a perspective view of a knock-over blade structure illustrating a knock-over band of the prior art;

FIG. 4 is a side elevation in partial section showing the needle bed structure of the present invention;

FIG. 5 is a perspective view of the structure according to the invention, with certain parts broken away and others in section, taken from the front of the needle bed;

FIG. 6 is an elevational view of the structure according to the invention, with certain parts shown in section, taken from the rear of the needle bed; and

FIG. 7 is an enlarged sectional view in side elevation showing more details of the novel structure of the present invention.

Initially, reference will be had to FIG. 1 which shows schematically various important operating elements of a Raschel machine to which this invention is applied. Thus, the warp yarn 20 is shown being drawn from the usual warp beam 21 over a diversion bar 22, over the yarn strip 23 of a pivotable tension arm 24, through the eyelet 25 of the usual movable guide 26 which, through well known motions, serves to lap the yarn 20 about the needles 27 prior to stitch formation.

As shown in FIG. 1, the machine is also equipped with the usual sinkers 28 which pass between the needles to hold the stitches below the latches of the needles as the needles ascend. This machine is also equipped with a needle bed generally indicated as 29 which includes a body portion 30 and trick blades 31 which form slots for accommodating the vertical movement of the needles 27. The top edges of the trick blades 31 cooperate in stitch formation by separating the stitches in the manner well known in the art.

The needle bed structure 29 shown in FIG. 1 also includes a knock-over band 32. The details of this band 32 will be explained subsequently, but for the present it is sufiicient to note that the top edge 32a of the band is positioned approximately at the top edge of the trick blades 31 so as to provide a surface over which the cast off stitches are drawn or knocked over as the tension. However, this resulted in the tight stitches bind-' ing about the hook and latch of theneedles to the point where cast-off could not be completed. Because the needles thus carried these stitches as they ascended, tension became excessive and the warp thread broke.

In modern times, one of the most commonly used needle bed structures has employed a pivotable band at the rear of the tricks to assist in knock-over of cast-off stitches. This arrangement is described in Noe US. Patents Nos. 2,749,729 and 2,749,730. Although this type of arrangement does facilitate knock-over to a degree, it

encounters limitations when the production of tight stitches at high speeds is desired.

To illustrate the latter point, the arrangement shown in the aforesaid patents has been illustratedin FIGS. 2 and 3 of the present drawings. This type of needle bed structure employs a body portion 36 and vertical trick blades 37 for the guidance of needles 38. As best shown in FIG. 2 this prior structure also employs a pivotable knock-over band 39 having a knock-over edge 39a. Thus,

incoming yarn 41 is wrapped about the needles 38 by the usual guide 42 and drawn through a previous stitch 43. As shown in FIGS. 2 and 3, the previous stitch 43 has already been cast off the needles 38 and is resting upon the edge 39a of thepivotable knock-over band 39.

To understand the drawbacks of the above prior art structure, it is important to realize that when the old stitch 43 was cast off the needles 38, the fabric take-up tension momentarily became greater than the tension on the incoming yarn 41. At this point, however, the take-up tension does not serve to pull the stitch 43 over the edge 39a of the knock-over band 39 because the frictional resistance between the stitch 43 and the edge 39a is greater than the resistance of the band 39 to movement. As a result, the band 39 swings outwardly carrying with it the stitch 43. This action, in turn, enlarges stitch 43 as shown in FIG. 2 by robbing yarn 41 via a new loop 44 which is in the process of being drawn by the needles 38. As explained in Patent No. 2,749,730, the stitch 43 is subsequently reduced in size, but only by yarn robbing in the reverse direction, i.e. as the needle descends further it increases the tension on the yarn which comprises cast off stitch 43 and as a result yarn is taken from said stitch 43. As this happens, the stitch 43 not only decreases in size but also carries band 39 back toward the trick blades 37. Thus, even at this point, the stitch 43 is not knocked over edge 39a. In fact, the knockover of stitch 43 is not completed until the needle with the new loop 44 rises to clearing position.

From the above general summary of the knitting operation which takes place in connection with the prior art needle bed structure shown in FIGS. 2 and 3, it will be understood that the use of a pivoting band or like device consumes a relatively great amount of time to complete the knock-over of the stitches and is accompanied by yarn robbing in both directions, the sawing motion of which is not only wearing on the guides and other knitting instrumentalities and upon the yarn itself, but which consumes valuable time, thus limiting the operating speed of the knitting machine.

To overcome the above defects and to provide Raschel and other warp knitting machines with a capability of satisfactorily knitting very tight stitches at extremely high operating speeds, I have invented the novel structure shown in detail in FIGS. 4-7.

FIGS. 4-7 show (steel) trick blades 31 which are cast into blocks such as 30 and 30 shown in FIG. 5. For purposes of clarity of illustration, only two of such blocks 30 and 30 have been shown in FIG. 5 and dotdash lines have been used to indicate that similar blocks are normally present in side-by-side relationship. The blocks 30, 30' are provided with holes 30a, 30a through which bolts are inserted for fastening the blocks to the usual bar (not shown) which extends lengthwise of the machine. I

As shown best in FIG. 7, the trick blades 31 are cast in block 30 in such a manner that the rear of the blades 31 are backed by a portion 30b of the casting. The portion 30b terminates along an edge designated as 300 as indicated in FIG. 6.

Inserted under tension into an angled slot in block 30 is a knock-over band 32, the top edge 32a of which is positioned approximately at the top edges 31a of the trick blades 31. Preferably, the band 32 is spring steel and is pressed into the slot in the block 30 under tension and in a curved condition so that its upper portion is constantly biased under spring pressure toward the rear of the trick blades 31. This, of course, together with the concave curvature of the band in a direction away from the trick blades, and the angled arrangement of the slot upwardly toward the trick blades, prevents the band 32 from swinging backwards during the knock-over process.

Using the needle bed of the present construction, it is possible to form very tight stitches and cast such stitches over edge 32a in a continuous operation, i.e. without intermediate enlargement and contraction of stitch size, at very high speeds. This is illustrated in FIG. 4 where the incoming yarn is shown having been drawn through the cast-off old loop 46. In contrast with the pivoting type of blade used in the prior art, the knockover band 32 of the present invention does not swing backwards when the fabric take-up tension, which is indicated by the arrow in FIG. 4, pulls the fabric 33 downwardly. Thus, the

cast-off stitch 46 is not permitted to enlarge in the manner-shown in FIG. 2, but is in fact tightened to an increased extent as it is pulled over the edge 32a of the knock-over band 32 in a continuous movement.

It is to be clearly understood that the terms and expressions used herein are employed as terms of description, and not of limitation, and that there is no intention in using such terms and expressions to exclude any equivalents of the apparatus described. It is-also .to be clearly understood that what is specifically shown and described herein represents a preferred embodiment only of the invention, and that various changes and equivalents may be resorted to without departing from the principles of the invention or the scope of the claim hereof. Accordingly, it is intended to claim the present invention broadly, as well as specifically, as indicated in the appended claim.

The following is claimed:

1. Needle bed structure for warp knitting machines comprising a plurality of spaced-apartgenerally vertically disposed trick blades providing open ended needle slots at the front and each having a side edge at the rear and a stitch separating edge at the upper end of the needle slots, a metallic block having said trick blades embedded therein, said trick blades and said block being formed with relatively deep slots providing a continuous lengthwise extending slot angled upwardly towards the rear edges of said trick blades, and an immovable thin spring steel band having its lower portion press-fitted into said lengthwise extending slot and having a curvature to bias the same against said rear edges, said band having a top edge extending slightly above the stitch separating edges of said trick blades to provide a knock-over edge for the needle bed structure.

References Cited UNITED STATES PATENTS 2,682,163 6/1954 Staff et al. 6686 2,749,729 6/1956 Noe 66-86 2,749,730 6/1956 Noe 6686 MERVIN STEIN, Primary Examiner.

R. FELDBAUM, Assistant Examiner. 

